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    <meta charset="UTF-8">
    <title>Title</title>
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{switch number}
{case 1}上{/case}
{case 2}中{/case}
{case 3|4|5}下{/case}
{default/}不存在
{/switch}


{if ($number>10) AND ($number==11) OR ($number==1)}
1
{elseif $number<0}
-1
{else/}0
{/if}

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<!--范围标签  in notin  between notbetween-->
{in name='number' value='10,20,30,40'}存在
{else/}不存在{/in}
{between name='number' value='-100,1'}存在
{else/}不存在{/between}

<hr>
<!--是否存在标签 present notpresent 判断变量是否已经定义赋值-->
{present name='number'}存在{/present}
<!--empty notempty 判断变量是否为空值-->
<hr>
{notempty name='number'}有值{/notempty}
<!--常量是否定义 defing notdefind-->
{define name='PI' value='3.14'}
{defined name='PI'}
PI存在{/defined}
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